When and how to take cold showers? Are they useful?

You will (most likely) never gain a complete knowledge about anything as there will always be different point of views and arguments for and against. I have myself been doing this for a year and it has had very good effect on my health. I tend to take them at least once every day (sometimes twice per day). However, cold-showers/cold-baths are about many things and have at least the following seven benefits:

-Increased alertness.
-Refines hair and skin.
-Improves your immunity and circulation.
-Stimulates weight-loss.
-Speeds up muscle-soreness and recovery.
-Easing of stress.
-Relieves depression.

On top of this, they also increase T-levels a little (most likely due to their connection to reason Nr.3 and 6). The info in this link explains shortly why you gain these benefits from cold-showers:

https://www.medicaldaily.com/benefi...y-taking-cool-showers-good-your-health-289524